Examinando por Autor "Hochberg, David"

Mostrando 1 - 5 de 5

Acceso Abierto
Chaotic oscillations, dissipation and mirror symmetry breaking in a chiral catalytic network
(Royal Society of Chemistry, 2020-11-12) Hochberg, David; Sánchez Torralba, Antonio; Morán, Federico; Agencia Estatal de Investigación (AEI)
Catalytic reaction networks consist of molecular arrays interconnected by autocatalysis and cross-catalytic pathways among the reactants, and serve as bottom-up models for the design and understanding of molecular evolution and emergent phenomena. An important example of the latter is the emergence of homochirality in biomolecules during chemical evolution. This chiral symmetry breaking is triggered by bistability and bifurcation in networks of chiral replicators. Spontaneous mirror symmetry breaking (SMSB) results from hypercyclic connectivity when the chirality and enantioselectivity of the replicators are taken into account. Heretofore, SMSB has been generally understood as involving chemical transformations yielding scalemic outcomes as non-equilibrium steady states (NESS). Here, in marked contrast, we consider the chaotic regime, in which steady states do not exist. The dissipation, or entropy production, is chaotic as is the exchange entropy. The rate of change of the total system entropy, governed by the entropy balance equation, is also chaotic. Subsequent to the mirror symmetry breaking transition, the time averaged entropy production is minimized in the final chaotic chiral state with respect to the former chaotic racemic state. The chemical forces (i.e., the affinities) evolve in time so as to lower the sum of the entropy production and the exchange entropy, in compliance with the general evolution criterion extended to reaction networks subject to volumetric open flow.
Restringido
Renormalization of stochastic differential equations with multiplicative noise using effective potential methods
(Physical Review E. covering statistical, nonlinear, biological, and soft matter physics, 2020-12-23) Gagnon, Jean Sébastien; Hochberg, David; Pérez Mercader, Juan; Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737
We present a method to renormalize stochastic differential equations subjected to multiplicative noise. The method is based on the widely used concept of effective potential in high-energy physics and has already been successfully applied to the renormalization of stochastic differential equations subjected to additive noise. We derive a general formula for the one-loop effective potential of a single ordinary stochastic differential equation (with arbitrary interaction terms) subjected to multiplicative Gaussian noise (provided the noise satisfies a certain normalization condition). To illustrate the usefulness (and limitations) of the method, we use the effective potential to renormalize a toy chemical model based on a simplified Gray-Scott reaction. In particular, we use it to compute the scale dependence of the toy model's parameters (in perturbation theory) when subjected to a Gaussian power-law noise with short time correlations.
Restringido
Renormalization of stochastic differential equations with multiplicative noise using effective potential methods
(APS Physics, 2020-12-23) Sébastien Gagnon, Jean; Hochberg, David; Pérez Mercader, Juan; Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737
We present a method to renormalize stochastic differential equations subjected to multiplicative noise. The method is based on the widely used concept of effective potential in high-energy physics and has already been successfully applied to the renormalization of stochastic differential equations subjected to additive noise. We derive a general formula for the one-loop effective potential of a single ordinary stochastic differential equation (with arbitrary interaction terms) subjected to multiplicative Gaussian noise (provided the noise satisfies a certain normalization condition). To illustrate the usefulness (and limitations) of the method, we use the effective potential to renormalize a toy chemical model based on a simplified Gray-Scott reaction. In particular, we use it to compute the scale dependence of the toy model's parameters (in perturbation theory) when subjected to a Gaussian power-law noise with short time correlations.
Restringido
Spontaneous Deracemizations
(ACS Publications, 2021-02-24) Buhse, Thomas; Cruz, José Manuel; Noble-Terán, María E.; Hochberg, David; Ribó, Josep M.; Crusats, Joaquim; Micheau, Jean Claude; National Science Centre, Poland (NCN); Agencia Estatal de Investigación (AEI); Gobierno de Canarias; 0000-0001-5082-0873; 0000-0002-0411-019X; 0000-0001-6258-1726; 0000-0003-3511-4676
Spontaneous deracemizations is a challenging, multidisciplinary subject in current chirality research. In the absence of any chiral inductors, an achiral substance or a racemic composition is driven into an enantioenriched or even homochiral state through a selective energy input, e.g., chemical potential, photoirradiation, mechanical grinding, ultrasound waves, thermal gradients, etc. The most prominent examples of such transformations are the Soai reaction and the Viedma deracemization. In this review, we track the most recent developments in this topic and recall that many other deracemizations have been reported for solutions from mesophases to conglomerate crystallizations. A compiled set of simply available achiral organic, inorganic, organometallic, and MOF compounds, yielding conglomerate crystals, should give the impetus to realize new experiments on spontaneous deracemizations. Taking into account thermodynamic constraints, modeling efforts have shown that structural features alone are not sufficient to describe spontaneous deracemizations. As a guideline of this review, particular attention is paid to the physicochemical origin and symmetry requirements of such processes.
Acceso Abierto
Thermodynamic evolution theorem for chemical reactions
(APS Physics, 2020-12-14) Hochberg, David; Ribó, Josep M.; Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737
The production, exchange, and balance of entropy characterize the thermodynamics of open nonequilibrium systems, ranging from chemical reactions, cells, ecological systems, and Earth-like planets to stars. We generalize the Glansdorff-Prigogine general evolution criterion to constrain the entropy balance in volumetric open-flow chemical reaction systems. We derive a thermodynamic inequality governing the joint evolution of both the internal microreversible reactions and the matter fluxes that the system exchanges with its environment, as exemplified by the distribution of the entropy productions and exchanges over the chemical reaction pathways. We validate this evolution theorem and discuss the physical significance of this pathwise partitioning of the dissipation, for an autocatalytic model capable of spontaneous mirror symmetry breaking.